Fuel burner interlocking safety control



March 9, 1954 c FUEL BURNER INTERLOCKING SAFETY CONTROL 3 Sheets-Sheet 2Filed Dec. 3, 1949 I N V EN TOR. IRA 6'. M (484'- March 9, 1954 I. E.MCCABE 2,671,502

FUEL BURNER INTERLOCKING SAFETY CONTROL Filed Dec. 5, 1949 3Sheets-Sheet 5 INVENTOR. m4 5. m up:

Patented Mar. 9, 1954 UNITED STATES PATENT OFFICE;

FUEL BURNER INTERLOCKING SAFETY CONTR 15 Claims.

This invention relates to a new and improved electrical controlapparatus and more particularly to apparatus of this character adaptedto control the operation of liquid or gaseous fuel burners.

In a specific form it relates to a relay for the control of burneroperating circuits, together with secondary circuits for control of theoperation of said relay and mechanical interlocks, certain interlocksbeing electrically operated while others may require manual operation.More specifi cally, the apparatus includes a relay which is dependentupon a combustion responsive control device for maintenance of the relayin operation, other means being provided to initially bring the relayinto operation and to maintain it in opera tion long enough for thecombustion responsive device to be affected by combustion and to comeinto operation. Should combustion fail to take place within aredetermined period, the appacondition a combustion responsive elementso that a burner circuit is closed to put a burner in opera.-- tion. Thedevice then includes means to take over the conditioning of the deviceand make it responsive to the existence of predetermined flame orcombustion conditions so that the control apparatus may continue runningof the burner as long as proper conditions prevail. A suitablecombustion responsive device is shown'in my co-pending applicationSerial No. 127,498, filed November 15, 1949-, which comprises a switch,the movable contact of which is moved in response. to the presence orabsence of light emanatingfrom the burner flame.

The present invention represents an improvement over such devicesdisclosed in my prior Patents Numbers 2,024,697 of December 17, 1935;2,075,951 of" A ril 6', 1937"; and 2,158,515 of May 16, 1939. In theapparatus disclosed herein, a time of operation-in responding tothe-absence of flame to shut down the burner and cut-off fuel eitherwhen attempting to establish the" flame or maintain it, is so muchfaster that it may be advantageousl'y' used in connection with controlof burners burning a high rateof fuel per hour.

It thus becomes-possible to use-with suchcapacityburners mechanicaldevices of the character herein disclosed which will assure positiveprotection against the delivery of large quantities of fuel Withoutmeans to ignite it and to terminate such delivery quickly upon flameextinguishment from causes other than a normal shut down of the burner.

It is an object of the present invention to provide relay controlapparatus which, when associated with a suitable combustion responsivedevice, will initiate burner operation and stop said burner operationupon failure of combustion to take place within a predetermined time.

It is a further object to provide such apparatus which will stop burneroperation should c0mbustion cease or be reduced below a predeterminedlevel after it has been initiated.

It is an additional object to provide apparatus having a plurality ofoperating stages and means for progressively attaining said stageswhereby the apparatus serves to initiate burner operation, provide atime delay to permit the operation to become effective and thereafterassume a stage of adjustment responsive to lack of illumination fromflame of combustion or reduction of illumination intensity below apredetermined level.

It is a further object to provide apparatus which will return to itsinitial position upon cutoff of current supply and will automaticallyrestore combustion upon resumption of current flow.

It is another object to provide apparatus of this character which willstop burner motor operation upon failure of ignition within apredetermined time and', also, upon interruption of flame propagationfor a predetermined time and which requires manual reset to restorenormal burner and control.

It is still another object to provide apparatus which will be dependentupon the proper functioning of a combustion responsive safety device inorder to initiate and maintain operation of the burner in response to ademand for its operation with each initiation of a burner operationrequiring the combustion device attaining its operative positionindicative of no combustion and the maintenance of burner operationrequiring the combustion device attaining its operative positionindicative of the presence of combustion and, further, that no operationof the burner may occur if the circuits controlled by the combustiondevice are improperly made or short circuited.

Other and further objects will appear as the description proceeds.

I have shown certain preferred embodiments of 3 my invention in theaccompanying drawings, in which- Figure 1 is a front elevation showingthe working parts of the control apparatus;

Figure 2 is a somewhat schematic wiring diagram of the apparatus and ofthe device controlled thereby;

Figure 3 is a horizontal section, partly broken away, taken on line 3-3of Figure 1;

Figure 4 is a fragmentary view, on an enlarged scale, showing the partsof the control in the idle position;

Figure 5 is a view similar to Figure 4 showing the parts under normalrunning conditions;

Figure -6 shows the parts in the automatic cutoff position; and

Figure 7 is a fragmentary view showing a modified form of safetylock-out construction with the parts in operating position.

In order to better explain the operation of the control apparatus,reference will be made first to the general circuit layout shown inFigure 2. Here, the control apparatus is shown as mounted on a base I Iand comprising a closed transformer core I3 secured to the base andcarrying the transformer primary coil I4 which is fixedly supportedthereon. One side of this primary coil I4 is connected through anormally closed safety lock-out switch I30 to terminal It, whil theother side of the coil is connected to terminal I8. The terminals I6 andI8 are fed from regular power line alternating current of standardvoltage, such as 115 volts, through the lines 29 and 2|. Thisapplication discloses different structures as regards the look-outsafety feature of the invention. One form, strictly mechanical, isdescribed with respect to its representation in Figure 6. In this formthe safety switch I30 may be omitted and the two sides of the primarycoil I4 connected directly to terminals IB and Ill. The other formincluding switch I30 is described in connection with a detailed showingof the switch operating structure in Figure 7.

Power line passes through a boiler limit control 23. It will beunderstood that this boiler limit control comprises a normally closedswitch. which, however, may be opened by abnormal boiler conditions,such as excess pressure or excess temperature. Such controls are wellknown and its specific construction forms no part of the presentinvention.

- The tiltable mercury switch is carried on one end of the rockablecarrier 26, the latter being pivoted at 21 on the transformer core I3.This mercury switch 25 is shown in Figure 2 in its open position, thetwo contact members of the switch being connected to the terminals l6and 29 respectively. The terminal 30 is directly connected to theincoming line terminal I8. Wires 32 and 34 lead from the terminals 29and 30 to the burner motor 36. The ignition transformer 38 is connectedin parallel with the burner motor 36 by the wires 39 and 4B. Theignition gap is shown at 42 with the grounded electrode 43. As thusshown, ignition is constantly provided as long as the burner motor isenergized. When it may be desired to cut off ignition a predeterminedperiod after initiating burner operation, any desired form of ignitioncut-off means may be interposed in the ignition circuit to accomplishthis. One such form may be that disclosed in my prior Patent No.2,287,386 of June 23, 1942.

The secondary coil 45 on the transformer core I3 is supported by therocking carrier 26 on the opposite side of the pivot 21 from the mercuryswitch 25. One side of the secondary 45 is connected to terminal 41,with the other side being connected to terminal 48. The light responsiveswitch 52 includes a fixed contact 5| which is connected by wire 52 toterminal 58. The switch 50 includes movable switch member 56 which isexternally connected to wire 51 leading to terminal 48. It will be notedthat, in the specific forms of construction shown, the fixed terminal 5|terminates in contact with a globule of mercury 59, a portion of themercury being drawn up in the capillary tube 60. The mercury in the tubeSi] is exposed through an opening 6I for engagement by the movablecontact 55. This movable contact is moved by expansion of the expandablemember 63. This member is expandable by the application of heat, eitherdirectly or as heat derived from the concentration of light rays of theflame upon the member 63. The member 63, being dark and opaque, absorbsthe light rays and the light energy is converted into a form of heatenergy.

The heating coil is connected at one end to the wire 51, this being thesame wire to which the moving contact 56 is connected. The other end ofthe heating coil 65 is connected by wire 61 to terminal 54. The roomthermostat 10 is connected by wire H to terminal 68 and by wire 13 toterminal 41. The solenoid coil 16 is connected by wire 11 to terminal 54and by wire 19 to terminal 68. This solenoid 16 is provided with a fixediron core 80.

The particular construction of the light and heat responsive switch 50forms no part of the present invention, this being covered by mycopending application Serial No. 127,498, filed November 15, 1949. Thethermostatic switch 15, also, forms no part of the present invention.This may be any standard type of heat responsive thermostat located in aroom or other space being heated by the apparatus which the presentdevice serves to control.

It will be apparent from an examination of the circuit diagram that,assuming the given boiler conditions are normal and the boiler limitcontrol 23 is in normal position with closed contacts, then theestablished line voltage is continuously applied through wires 20 and 2|and terminals I5 and I8 to the primary I4 of the transformer. Thistransformer is of th relay type with the secondary 45 pivotally mountedon the rocking carrier 26, as has been described. When the transformersecondary 45 is included in a closed circuit of. such character that itdraws a substantial amount of current, the magnetic repulsion is suchthat the secondary 45 is thrust away from the primary I4. This causesthe car-' rier 26 to rock in the counterclockwise direction about itspivot 21 which tilts the mercury switch 25 to such a position that themercury therein closes the circuit through the switch. It will beapparent that, when the circuit is closed through the switch 25, linecurrent is supplied through the switch both to the burner motor 35 andthe ignition coil 38.

However, this action only takes place when a closed circuit is providedincluding the secondary 45, the circuit drawing suificient current tocause the necessary magnetic repulsion. It will be apparent that thecircuit through secondary 45 may be closed through terminal 48, wire 51,movable switch contact 56, fixed switch contact 5 I, wire 52,

terminal 68. wire 1|, thermostat 10, wire 13 and back through theterminal 41 to the other side of the secondary. It will be noted,howeventhat under-normal conditions-,gwiththe motor oitand fireout, theswitch 5.6 is:open so. that thecircuit will not be closed as described;.Analternatecircult: extends from the: secondary 45 through terminal 48',line heating: resistance. 65,.linezfil, terminal: 54 ,.line; 1.1-,solenoid 1.6,. line 1.9, terminal 63,, line 1 I ,.r.oom:, thermostat l0and: line 13 backto terminal 4]. In thiscase; both the. heating coil fiiandsolenoid coil 16 are connected in series with;the= secondary 4.5: It.will be further noted, however, that.v the circuit doesxnotibe'comeclosed. until. the room. thermostat becomes closed under: thetemperature conditions: for which that thermostat adjusted.

Whenthealternate circuit is closedby: the room. thermostat; currentflows through. the transformer: secondary: circuit but, with the heatingcoil 65and/or-solenoid16 being included therein, sufilcient resistanceis interposed inthe circuit'to reduce the current flow: so thatrepulsion of the secondary coil does not occur; heating: coilisenergized and it will be apparent thattheheating coil 65, beinginclose proximity to the expandablemember 63, will heat that member to.such an extent as to swing'the-moving contact 56 into-engagement withthe mercury at El: and" establish a circuit through the mercury pool at59 through. fixed contact 51 and back through line 52 to'the terminal68. Thus, as previously described, the secondary circuit acrossterminals 41-48, including the relay secondary 45 and thermostat I0; iscompleted and, as a result, the alternate circuit, including the heatingcoil B5 and solenoid' 16', is shunted where'- upon magnetic repulsion:of the secondary coil" occurs to close the mercury switch 25. Uponinitiating burner operation, the establishment of flameprovides asourceof' light from which the switch derives heat to maintain the expandable-member 63 inheated condition, which heat replaces thatcut off' whenthe heating coil 65 is shunted. The member 63 is adapted to'be exposedto the light radiating from the burnerflame and, being dark and opaque,light rays are absorbed and the light energy converted into heat. Theexpandable member 63 is heated sufficiently by the heating coil 65, wheneifectinga closure of the switch contact, that opening-of the switchcontact upon de-energization' of the coil will not take place before apredetermined lapse of time which is of such duration that, normally,establishment of combustion and heating of member 63 by radiant energywill occur-to maintain the contact in closed position. Therefore, withthe normal establishment of combustion, the switch 50 remains closedafter de-energization of the heating coil 65' and will remain closed forcontinued operation of the-burner as longas the demand for same is made"and the burner flame exists.

The motor circuit must, however, be opened if a flame fails to appeartoactuate the switch 50' afterthe lapse of time providedfor'establishment of combustion occurs. This control is adapted foruseinconnection withburners using subs-tam tial quantities of oilperminuteand, if the burner is operating but. the. liquid fuel is notignited, there will be not only substantialv losses of. fuel, but fuelwill flow into the combustion. chamber in quantities which can become.very dangerous.- Itis important, therefore, that the control be. so'designed that it not only terminates operation of the motor 36 and,consequently, flow of fuel when thefiame isextinguishedfor any reasonbut-,also, mustrtpromptly take the same action. if. the. fuel.

However, the

failsto. ignite and produce-a flameinacompara: tively. short time afterthe motorisput. in opera-.-

tion. 1

They apparatus is-designed to. take careof; these several contingenciesand: the. various interlocks: of: themechanical means: controlling themove;- ment of therocking-carrier 26 and, consequently, the motorcircuit. controlled: by the: mercury switch 25 areshown in Figure 1innormalinactive view and are shown on. an enlarged. scale: in Fig.-:ures:3-. to. 6.. inclusive.

Referring first to Figure 4 showing the: parts in the-idle position,that: is, with the burner motor off, the relay release catch'iliismounted to swing. freely onthe pivot 86, being held. inv position. on;the pivot by the u-ring 81. The release.v catch is' so weighted:relative to its pivot 86*that. it would. be normally positioned. bygravity in a position. swung slightly counter-clockwise from thatirrwhich it is shown in Figure 4 were it not. for the interposition of the.stop. arm 93'. The relay release lever is'pivoted on the fixed pin. 91,this. relay release having the transversely extending stop. arm 93, oneedge of which is adapted to engage the shoulder 94 formed. onv the lowerportion of the relay releasecatch '85. In other positions of. the parts,this stop arm 93 passes above. the ledge 95' which. is locatedimmediately above: the shoulder 94.

The relay release catch 85 is provided with a contact finger 91 which,in certain positions of the parts, engagesthelower-transversely"extend-- ing abutment portion. 99 of the safetylatch car-- rier. Hll The relay release 90 is further provided with an.upwardly.- extending portion I03, upon the forward. face of which issecured a small iron section I05 adapted to be attracted by the core 80of the solenoid iii-when thatsol'enoid is energized. The safety latchcarrier I01 is shown as pivoted on thepivot member 21 to which ispivoted the carrier 26Jcarrying the transformer secondary 45;This'safety latch carrier HII', however, is movable on the pivotentirely independ ent ofmovement of thecarrier 26which supportsthesecondary 45', but is weighted to the right of itsfpivot so asto assumeaposition by gravity normally resulting in its movement asa unit withthe secondary coil 45. This safety latch carrier lill. has an inturnedportion at 101 to which is connected an arm I08 extendingparallel withthe main portion off'the safety latch carrier I Ill. An iron section I09is secured to the arm I08 so that, when placed inthe proximity of core80 of solenoid 16, it may beattractedby the core when the solenoid isenergized.

The safety latch III is pivoted at Hi! upon the" safety latch carrierllll. This safety latch has: an operating arm H3 which may beengaged.manually or by any desired operatingnreans, not shown, for swinging thesafety latch H1l in the: counterclockwise direction about itspivot H2. Asafety catch H5 is secured tothe relay secondary construction by thescrew- H6; This? catch H5; therefore, moves with the secondary' 45 andindependently of" the latch IH. The safety latch HI' isprovided' with anotch 8' adapted, under certain conditions, to engage the left side ofthe safety catch H5, as shown, for example,. in Figure 6.

The repulsion of the secondary 45 normally causes movement of; the latchcarrier I'DI, which. is moved by and. with the. secondary since theupper corner l2! of the secondary carrier assembly engagesvthe.transversely extending nortioni l'llJ- of; the safety latch carrier,which car rier is weighted to the right of the pivot 21 whereby itassumes, by gravity, its position in abutment with corner MI. The safetylatch II I carried by the safety latch carrier l9l normally rests uponthe safety catch I 15, as shown in Figures 1 and 4, so that this latchIll moves with the carrier l9l as a unit with the secondary coil 45 asit swings about its pivot 21.

Theapparatus i shown in its normal or nonoperating position in Figure 4of the drawings, in which case the secondary 45 is swung downwardlyimmediately adjacent the primary. The parts are also shown in thisposition in Figure 1; In this position, the relay release lever 99 hasits stop arm 93' in abutment with portion 99 of the safety latch carrierI9l in substantially direct alignment with the relay release lever pivot9| so that, with the parts in this position, the stop arm 93 preventsthe secondary 45 from being swung upwardly and, as a consequence,prevents the mercury switch 25 from being swung to the operative orclosed position.

When the initial circuit is closed by means of room thermostat I9, theelectromagnet 16 is energized and attracts the magnetic section I95carried by the relay release member 99, thus lifting the stop portion 93of the relay release lever 99 so that it clears the shoulder 94 and alsoclears the abutting portion 99 of the safety latch carrier l9l.

' When the flame switch 59 becomes operative and closes to establish therunning circuit, the secondary 45 is repelled and assumes the positionshown in Figure 5. This flame switch 59 is initially operated by heatderived from the resistance coil 65 which, as has been previouslydescribed, is placed in the circuit at the same time as the solenoid 16of the electromagnet. It is to be understood that the manner ofoperation of the flame switch 59 is such that light rays from the flamefocused upon the temperature responsive element 63 will maintain theelement heated and maintain the switch circuit closed after the heatingcoil 95 is de-energized. De-energization of the heating coil 65, as wellas the solenoid 19, occurs with the closure of the switch 59, aspreviously described.

Relay devices of the character and for the purposes herein disclosed areintended to operate to provide a closure of the relay switch, that is,

the mercury switch 25, at a voltage not less than below the ratedvoltage of the relay. At the lower portion of its operating range, therepulsion of the relay secondary is not as forceful as under the highervoltage conditions prevailing at the upper portions of its operatingrange. Since the magnet 16 is de-energized at the time of the repulsionof the secondary 45, it would not be desirable for the relay release 99,with its stop member 93, which release is no longer held by magnet 15,to fall back to block the repulsion of the secondary 45 when themovement of this secondary is slow due to low voltage conditions. Ifsuch a low voltage condition exists, the relay release catch 85preventsthe dropping of the relay release stop portion 93 to a blocking positionupon de-magnetization since the portion 93 rests on the ledge 95 of thecatch 85. As has been stated, the catch 95 is so balanced that gravitycauses it to swing under the relay release portion 93 when that portionis lifted above the shoulder 94. This permits the secondary to continueto move to its repelled position, whereupon the relay release catch 85is swung to the left or. in; the cl ockwise direction about its pivot 96by contact of the lower finger 91 with the abutment portion 99 of thesafety latch carrier I9l,*as shown in Figure 5. I

Figure 5 shows the position of the parts under normal runningconditions. Here, the secondary coil 45, safety latch Ill and the safetylatch carrier I9l have moved upward as a unit andthe burner switch 25 isclosed. During this movement, the abutment 99 of the carrier I9! hasengaged the lower end 91 of the relay release catch 85 to release threlay release member 99 which, being no longer held by the magnet I6,drops back to its idle position. In this position, the stop portion 93is in a slot I22 formed in the latch carrier I9l above the abutmentportion 99.

It is to be noted here that should a current interruption of a momentarynature take place in either the primary [4 or the secondary 45,resulting in the de-energization of the secondary, it will fall back toits position, as shown in Figs ures 1 and 4, and this will restore therelay re.-: lease latch 99 and its portion 93 to the, position shown inFigure '4, preventing repulsion of the secondary coil 45 even thoughcurrent be restored to the primary and secondary after its interruption.What is now required to restore operation of the control apparatus is anopening of the circuit passing through the flame switch 59 which, in theform of construction disclosed, occurs in about five seconds, providedthe heater therein is not contributing any heat. In case the heater 65has been in circuit, the time may approach a maximum of fifteen seconds.With the opening of the contact 56 of the flame switch 59, the circuit,including the electromagnet I6, is restored, the relay release 93freeing the safety latch carrier MI and permitting the device to againreach the running position of Figure 5, as has been previouslydescribed.

Figure 6 illustrates the parts in the position assumed when throughfailure of ignition of the burner, no flame has been established to maintain the heating of the actuator or expandable member 93 of the flameswitch 59, which heating is required to maintain the contact 56 closed,after de-energization of the heating coil 65. The parts will take thesame position when, after the flame has been ignited, it goes out andthere is a cessation of heat emanating from the light rays of the flame.With regard to the operation upon ignition failure, attention is invitedfirst to the parts as shown in Figures 2 and 5. It is to be noted thatwhen the heater 65 of the flame switch causes closure of the contact 59therein to complete the running circuit, the repulsion of the secondary45 which takes place places the upper left extremity I99 of the safetylatch carrier' MI in the magnetic field zone of the magnet. At thistime, however, by virtue of the fact that the running circuit isenergized, the magnet 16 is de-energized. The burner switch beingclosed, combustion and establishment of a flame for maintaining theflame switch 59 closed should take place. If this does not take place,flame switch 59 will open circuit, thus restoring the initial controlcircuit, which includes the electro-' magnet 19 and the flame switchheater 65. Two different actions now take place. First, energization ofthe magnet 16 causes it to attract and hold the magnetic section I99 ofthe safety latch carrier l9! which holds that carrier in the position ithad assumed upon closing of the flame switch 59 by the heater 65therein. Second, the establishment of the preliminary control circuitwhen the flame switch 59 opened restored the resistance of the magnetcoil 16 and the switch heater 65 into the circuit of the secondary coil45, which results in reducing the value of the current passing throughthe secondary below that required to maintain the secondary repelledfrom the primary and in its upper position, as shown in Figure 5. Thesecondary 45 thus falls and the parts assume the positioni-n which theyare shown in Figure 6. Thus, in Figure 6, the magnetic portion I09 ofthe safety-latch carrier IOI is in contact with the core80 of the magnetHi, holding the carrier IIII in its upper position while, on the otherhand, the secondary 45 has fallen to its lowerp'osition where 'i t'restson the primary I4.

The safety latch III carried by the carrier 'IUI, which latter is heldbythe magnet 15,:also assumes a'position swung to'the left, as viewed inFigure 6,. so that the safety catch notch I I8 has passed over thesafety catch -I I5. With the parts in this position, as the heater 65 inthe flame switch 50 is caused to heatand to close the-switch 58, theexpected repulsion of the secondary coil 05 to close the mercury switch25 does not take place because the relay safety catch I I5 engagesthe-notch H8 and its upward movement is arrested. As long as the circuitof the room thermostat I remains closed, there'will occur a con--tinuous opening and closing of the contact 55 of the flameswitch 50 byvirtue of the alternate energization of the preliminary circuit and therunning circuit through the heating and cooling of the:expandable'element 63 of the flame switch 50, but without resulting inthe closing of the mercury switch 25.

The safety latch II I is provided, however, at its left end with theextension piece of actuating member II3 which is adapted to be engagedby any suitable means, not shown, whereby the lower portion of theextension I'I'3 may be pushed laterally to the right to swing the safetylatch II I around its pivot I I2 in the counter-clockwise direction.This movement will free the notch II8 of the safety latch from the latchmember H5 and permit a subsequent repulsion of the secondary coil totake place so that the parts will return to the position shown in Figure5.

This will again close the circuit through the motor switch 25 and putthe burner into operation. Should the "burner again fail to ignite, thepreviously described action will take place and the secondary will againdrop down, the latch II 5 again engaging the notch 'I I8.

The form of construction shown "in Figure '7 is generally similar inconstruction to that shown in Figure 6 but is provided with a differentform of latch and a normally closed mercury switch I 30 connected in theprimary circuit as shown in Figure 2 or, if desired, interposed in theburner motor circuit. This switch I30 and its associated structureaccomplishes the same result of shuttingdown the burner after ignitionfailure until corrective measures have been taken to assure ignition andthe control reset as the struc ture of Figure 6. Whereas ignitionfailure with the structureof Figure 6 results in the mechanical lock-outof the burner switch 25, the modification shown in Figure '7accomplishes the same result by opening the normally closed mercuryswitch I30. The apparatus includes the electromagnet having the solenoidcoil "16 and core 80. The secondary coil 45 is supported on the carrier26 pivoted on pin 21. A mercury switch I30 is carried by the bell cranklever I32 which is'pivoted on the pin I34. The bell crank I32 has a longarm I35 carrying a roller I31 near its upper end, the arm and rollerbeing of such weight that with their long lever arm they tend, bygravity, to swing the bell crank lever I32 in the clockwise directionabout the pivot pin I34. The lever I32 and switch I30 are shown in Figure '7 in the closed circuit position.

"A roller engaging member I38 is pivoted on pin 21 in the same manner asthe latch carrier IOI of the other form of construction, and moves'in'the counter-clockwise direction with repulsion of the secondary 45.The member I38 has an upwardly extending arm I40 whichha's an upperarcuate surface [+32 upon which the roller I3! may rest. The member I38also has'a forwardly extending arm I44 carrying an iron section I45adapted to be attracted bythe magnetized core of the electromagnet. Thefixed track member I fl is carried by the secondary 45 and always movestherewith. Thismember I41 has an upper arcuate surface I48 which, asshown in Figure '7, serves as a continuation of the arcuate surface I42of member I38.

In the operation of this form of construction, when the flame goes outor there is failure or initial ignition, and the first control circuitis again closed as described in connection with the form of constructionshown in Figures 1 to 6, the solenoid l6 isenergized and core 80attracts and holds magnetic member I45, thus holding the member I38 inthe position shown in broken lines in Figure 7. At this time, thecurrent flow through the secondary 45 is inadequate to maintain itrepelled from the primary and the secondary returns to the full lineposition of Figure '7 carrying with it the fixed track member *IE'I,upon the upper arcuate surface of which the roller I31 has been resting.This roller then drops down between the rear of the upwardly extendingarm I40 of the member I38 and the front of the member I47. This movementis caused by gravity and the switch I30 is swung upwardly and opens thecircuit. The switch I30 is normally connected in the main circuit to thetransformer primary and, when open, cuts off all current to theapparatus. To resume operation again, the switch is reset by manuallyrotating the bell crank I32, carrying theswitc'h I30, in thecounter-clockwise direction to restore it to the position shown inFigure 7. When the bell crank is so rotated, the member I38 will dropback by gravity as the electromagnet is no longer energized and allparts will be restored to the full line position of Figure 7 with thepin I31 resting on the arcuate surface I42.

The repulsion relay, as shown in the drawings and described, is arrangedto operate on alternating current with low voltage current'bein'ginduced in the secondary when the relay is energized. It is to beunderstood, however, that the relay may be adapted to direct currentapplications by properly connecting the pair of coils together so thatone is repelled from the other. when both are energized.

The invention, as disclosed herein, comprises a controlling device forliquid or gaseous fuel burners meeting the aforementioned objectives in'a manner which renders its operation dependent upon proper functioningof a combustion device, which latter device is responsive to normalcombustion conditions to permit burner operation and responsive toabnormal combustion conditions, or, failure to attain combustion, toprevent burner operation. With the combustion responsive device actingas a safeguard against burner operation under abnormal conditions, thepresent invention provides that com bustion be attained and continuedthereafter through the process if a particular sequence of controloperation and only of the combustion responsive device, upon whichsequence of operation is made dependent, is operative to perform itssafeguarding functions against the establishment of hazardousconditions. Each recurring operation of the burner, after a shutdown,must await the return of the combustion responsive device to its normalstarting position and the operation of the burner, upon the properfunctioning of the combustion responsive device upon initiating andestablishing combustion.

While certain preferred embodiments of the invention have been shown,they are to be understood to be illustrative only as it is capable offurther variation to meet diiiering conditions and requirements, and Icontemplate such modifications as come within the spirit and scope ofthe appended claims. Also, the apparatus may be used with other devicesthan the flame switch disclosed in my co-pending application to whichreference has been made. Other forms of electrothermal actuators may beused in the initiating circuit to close the switch establishing therunning circuit and other forms of combustion responsive switches may beused to parallel the electrothermally actuated switch to maintain therunning circuit, permitting the electrothermal actuator to cool and openits switch.

I claim:

1. Fuel burner control apparatus comprising a relay having actuatingmeans for closing connections to a burner circuit, means for energizingsaid relay to operate said actuating means, an initiating circuitincluding said relay energizing means, resistance of such value as toprevent passage of sufficient current to operate the relay and anelectromagnet; a low resistance shunt relay operating circuit,mechanical means for blocking the actuating means, said means beingmovable to unblocking position by attraction of said electromagnet uponenergization of the initiating circuit, and means responsive toenergization of the initiating circuit to elfect closure of the shuntcircuit reducing the resistance and permitting operation of theunblocked relay and responsive to combustion to maintain the shuntcircuit closed while combustion continues.

2. Fuel burner control apparatus comprising a relay having actuatingmeans for closing connections to a burner circuit, means for energizingsaid relay to operate said actuating means, an initiating circuitincluding said relay energizing means, resistance of such value as toprevent passage of sufficient current to operate the relay and anelectromagnet; a low resistance shunt relay operating circuit,mechanical means for blocking the actuating means, said means beingmovable to unblocking position by attraction of said electromagnet uponenergization of the initiating circuit, means responsive to energizationof the initiating circuit to effect closure of the shunt circuitreducing the resistance and permitting operation of the unblocked relayand responsive to combustion to maintain the shunt circuit closed whilecombustion continues, and a latch for blocking further operation of theactuating means, said latch being rendered operative by attraction ofsaid electromagnet upon restoring the initiating circuit followingcombustion failure.

3. Fuel burner control apparatus comprising a relay having actuatingmeans for closing connections to a burner circuit, means for energizingsaid relay to operate said actuating means, an initiating circuitincluding said relay energizing means, resistance of such value as toprevent passage of sufficient current to operate the relay and anelectromagnet; a low resistance shunt relay operating circuit,mechanical means for blocking the actuating means, said means beingmovable to unblocking position by attraction of said electromagnet uponenergization of the initiating circuit, means responsive to energizationof the initiating circuit to effect closure of the shunt circuitreducing the resistance and permitting operation of the unblocked relayand responsive to combustion to maintain the shunt circuit closed whilecombustion continues and upon combustion failure to open the shuntcircuit and restore the initiating circuit, a normally closed switchcontrolling the burner circuit, and means responsive upon restoring theinitiating circuit and subsequent operation of the relay to open theburner circuit, to open the normally closed switch.

4. Fuel burner control apparatus comprising a repulsion type relay,connections for closing a burner circuit upon actuation of the relay,mechanical means normally blocking repulsion of the relay secondary, aninitiating circuit including the relay secondary, resistance of suchvalue as to prevent passage of repulsion current through the secondaryand electrical means for unblocking the secondary; a low resistanceshunt relay operating circuit including the relay secondary. theinitiating circuit when energized operating the means for unblocking thesecondary, and means responsive to energization of the initiatingcircuit to effect a closure of the shunt circuit reducing the resistanceand permitting re pulsion of the secondary and responsive to combustionconditions to maintain the shunt circuit closed while combustioncontinues.

5. Fuel burner control apparatus comprising a repulsion type relay,connections for closing a burner circuit upon actuation of the relay,mechanical means normally blocking repulsion movement of the relaysecondary, an initiating circuit including the relay secondary,resistances of such value as to prevent passage of repulsion currentthrough the secondary and electrical means for unblocking the secondary;a low resistance shunt relay operating circuit including the relaysecondary, said initiating circuit when energized operating the meansunblocking the secondary, means for maintaining the secondary unblockeduntil said secondary has been moved to operating position, and meansresponsive to the energization of the initiating circuit to eflectclosure of the shunt circuit reducing the resistance and permittingrepulsion of the unblocked secondary and responsive to combustionconditions to maintain the shunt circuit closed whilecombustioncontinues.

6. Fuel burner control apparatus comprising a repulsion type relay,connections for closing a burner circuit upon actuation of the relay, aninitiating circuit including the relay secondary, resistances of suchvalue as to prevent passage of repulsion current through said secondary,and

' an electromagnet; a low resistance shunt relay operating circuitincluding the relay secondary, mechanical means for blocking repulsionof the secondary, said means being movable to unblock-.. ing position byattraction of said electromagnet :upon .energization of the initiatingcir'cuit, a-nd means responsive to the venergization of the initi-.a'ting circuit to effect closure of the shunt circuit reducing :theresistance, said last named means permitting repulsionof the unblockedsecondary and being responsive to combustion conditions to maintain theshunt circuit closed while combustion continues.

- '7. Fuel burner control apparatus comprising a repulsion type relay,connections for closing a burner circuit upon actuation of the'relay, aninitiating "circuit including the relay secondary, resistances of suchvalue as to prevent passage of repulsion current through said secondaryand an lectro-magnet; a low resistance shunt relay operating circuitincluding the relay secondary, mechanical means for blocking repulsionof the secondary, said means being movable to unblocking position byattraction of said electromagnet upon energizaticn of the initiatingcircuitgmeans responsive to the energization of'the initiating circuitto effect closure of the shunt circuit reducing the resistance andpermitting repulsion of the unblocked secondary, and responsive tocombustion conditions to maintain the shunt circuit closed 'whilecombustion continues and upon combustion failure to open the shuntcircuit and restore the initiating circuit, and a latch for blockingfurther repulsion of the sec- 'ondary, said latch being renderedoperative by attraction of said electromagnet upon restoring theinitiating circuit following combustion failure.

8. Fuel burner control apparatus comprising a repulsion type relay,connections for closing a burner circuit upon actuation-of the relay, apivoted carrier for the relay secondary, a burner circuit switchoperable by movement of the carrier, an electromagnet adjacent thesecondary, a relay release lever pivoted adjacent the relay secondary,said release lever having a magnetic member in operative relationshipwith the elec-- tromagnet and having a portion normally blockingmovement of the relay secondary, attraction by the electromagnet servingto move the block .ing portion to unblocking position to permitoperation of the relay to close the burner circuit switch, and a pivotedrelease levericatch adapted to engage and hold the release lever whensaid lever is moved to unblocking position, said catch being movable tobecome disengaged from said release lever upon repulsion of the relaysecondary.

9. Fuel burner control apparatus comprising a repulsion type relay,connections for closing a burner circuit upon actuation of the relay, apivoted carrier for the relay secondary, a burner circuit switchoperable by movement of the carrier, an electromagnet adjacent thesecondary, a relay release lever pivoted adjacent the relay secondary,said release lever having a magnetic member in operative relationshipwith the electromagnet and having a portion normally blocking movementof the relay secondary, attraction by the electromagnet serving to movethe blocking portion to unblocking position to permit operation of therelay to close the burner circuit switch, safety latch mechanism carriedby the pivoted carrier, said mechanism including a magnetic member movedto operative relationship with the electromagnet upon operation of therelay to close the switch, said safety latch being put in operation bythe electromagnet and the subsequent actuation of the relay toinoperative position to block therieafter :furth'er operationtot therelay to close the switch.

10. Fuel burner control apparatus comprising a repulsion type relayhaving a fixed *coil :and a movable coil, connections for closing aburner circuit upon repulsion of the movable coil, an initiating circuitincluding the movable coil, =resist'a'nces of such value as to preventpassage or the repulsion current through the movable coil "and anelectromagnet; a low resistance shunt operating circuit including themovable coil, mechanical means for blocking repulsion *of the movablecoil, said means being movable to =un= blocking position by attractionof said electromagnet upon energization of the initiating cir cuit,means responsive to the energization of the initiating circuit to effectclosure of the shunt circuit reducing the resistance and permittingrepulsion of the unblocked movable coil, and responsive to combustionconditions to maintain the shunt circuit closed while combustioncontinues and upon combustion failure to open the shunt circuit andrestore the initiating circuit, and means responsive upon restoring theinitiating circuit and subsequent movement of the movable coil to openthe burner circuit to prevent further'closure of the burner circuit.

11. Fuel burner control apparatus comprising a repulsion type relayhaving a fixed coil anda movable coil, an initiating circuit includingthe movable coil, resistances of such value as to .prevent passage ofrepulsion current through the movable coil and an electromagnet; a lowresistance shunt operating circuit including the movable coil,mechanical means for blocking repulsion of the movable coil, said meansbeing movable to unblocking position by attraction of said electromagnetupon energization of the initiating circuit, means responsive to theenergize,- tion of the initiating circuit to efiect closure of the shuntcircuit reducing the resistance and permitting repulsion of theunblocked movable coil, and responsive to combustion conditions tomaintain the shunt circuit closed while combustion continues and uponcombustion failure to open the shunt circuit and restore the initiatingcircuit, connections for closing a burnercircuit upon repulsion of themovable 0011, a normally closed switch controlling the burner circuit,and means responsive upon restoring the initiating circuit andsubsequent movement of the movable coil to open the burner circuit toopen the nor;- mally closed switch.

12. Fuel burner control apparatus comprising a relay having actuatingmeans for closing connections to a burner circuit, means for energizingsaid relay to operate said actuating means, an initiating circuitincluding said relay energizing means, resistance of such value as toprevent passage of sufficient current to operate the relay and anelectromagnet; a low resistance shunt relay operating circuit,mechanical means for blocking the actuating means, said means beingmovable to unblocking position by attraction of said electromagnet uponenergization of the initiating circuit, means responsive to theenergization of the initiating circuit to effect closure of the shuntcircuit reducing the resistance and permitting operation of theunblocked relay and responsive to combustion to maintain the shuntcircuit closed while combustion continues and upon combustion failure toopen the shunt circuit and restore the initiating circuit, and meansresponsive upon restoring the initiating circuit and subsequentoperation of the relay to open the burner circuit to prevent furtherclosure or the burner circuit.

13. Fuel burner control apparatus comprising a relay having actuatingmeans for closing connections to a burner circuit upon actuation of therelay, mechanical means normally blocking operation of the relayactuating means to prevent closure of the burner connections, electricalmeans for moving the mechanical means to unblocking position, aninitiating circuit including the relay actuating means, resistance ofsuch value as to prevent passage of suflicient current to operate therelay actuating means, and the electrical means for moving themechanical means to unblocking position, the initiating circuit whenenergized operating the said electrical means and moving the mechanicalmeans to unblocking position, a low resistance shunt relay operatingcircuit including the relay actuating means, means responsive toenergization of the initiating circuit to effect a closure of the shuntcircuit and operation of the relay actuating means and responsive tocombustion conditions to maintain the shunt circuit closed whilecombustion continues.

14. Fuel burner control apparatus comprising a relay having actuatingmeans for closing connections to a burner circuit upon actuation of therelay, mechanical means normally blocking operation of the relayactuating means to prevent closure of th burner connections, electricalmeans for moving the mechanical means to unblocking position, aninitiating circuit including the relay actuating means, resistance ofsuch value as to prevent passage of sufiicient current to operate therelay actuating means, and the electrical means for moving themechanical means to unblocking position, the initiating circuit whenenergized operating the said electrical means and moving the mechanicalmeans to unblocking position, a low resistance shunt relay operatingcircuit including the relay actuating means, means responsive toenergization of the initiating circuit to effect a closure of the shuntcircuit and operation of the relay actuating means, and responsive tocombustion conditions to maintain the shunt circuit closed whilecombustion continues, said last named means including a switch forclosing the relay operating circuit, said switch being heat responsiveand being in heating relationship to resistance in the initiatingcircuit whereby the relay operating circuit is closed a. predeterminedtime after the initiating circuit is closed.

15. Fuel burner control apparatus comprising a relay having actuatingmeans for closing connections to a burner circuit upon actuation of therelay, mechanical means normally blocking operation of the relayactuating means to prevent closure of the burner connections, electricalmeans for moving the mechanical mean to unblocking position, aninitiating circuit including the relay actuating means, resistance ofsuch value as to prevent passage of sufllcient current to operate therelay actuating means, and the electrical means for moving themechanical means to unblocking position, the initiating cir cuit whenenergized operating th said electrical means and moving the mechanicalmeans to unblocking position, a low resistance shunt relay operatingcircuit including the relay actuating means, means responsiv toenergization of the initiating circuit to effect a closure of the shuntcircuit and operation of the relay actuating means, and responsive tocombustion conditions to maintain the shunt circuit closed whilecombustion continues, said last named mean includ- 1 ing a switch forclosing the relay operating circuit, said switch being heat responsiveand being in heating relationship to resistance in the initiatingcircuit whereby the relay operating circuit is closed a predeterminedtime after the initiating circuit is closed, and a latch for blockingfurther operation of th relay actuating means, said latch being renderedoperative by the electrical mean for moving the mechanical blockingmeans upon restoring the initiating circuit upon combustion failure.

IRA E. McCABE,

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,594,020 Smith July 27, 1926 1,674,051 McCabe June 19, 19281,881,321 McCabe Oct. 4, 1932 2,057,383 Kroger Oct. 13, 1936 2,068,425McCabe Jan. 19, 1937 2,102,618 Francis Dec. 21, 1937 2,159,658 Hall May23, 1939 2,171,860 McCabe Sept. 5,1939 2,550,507 Wellman Apr. 24, 1951

